**Table 3:** Best-fit parameters of the multi-component model WABS( BB + EQPAIR + Gaussian) for the first and second observation of GX 17+2. The F-test gives the probability of chance improvement of the $\chi ^2$ switching from thermal to hybrid Comptonization. The compactness parameters $\ell _{\rm s}$ , $\ell _{\rm h}$ and $\ell _{\rm nth}$ are defined in Sect. 3.3. The ratio $L_{\rm bb}/L_{\rm tot}$ is computed in the energy range 0.4-200 keV.
Parameter	Obs. 1	Obs. 2
	I	II+III+IV
$N_{\rm H}^{\rm a}$	$\rm 2.00^{+0.05}_{-0.05}$	$\rm 1.97^{+0.07}_{-0.06}$
$kT_{\rm bb}$ (keV)	$\rm0.58^{+0.02}_{-0.01}$	$\rm0.60^{+0.01}_{-0.02}$
$R_{\rm bb}$ (km)	$\rm 33^{+2}_{-2}$	$\rm 31^{+3}_{-3}$
$kT_{\rm s}$ (keV)	$\rm0.88^{+0.14}_{-0.08}$	$\rm0.95^{+0.03}_{-0.05}$
$kT_{\rm e}$ (keV)	3.5	3.5
$\ell _{\rm s}$	$\rm 7600^{+7000}_{-3400}$	[7600]
$\ell_{\rm h}/\ell_{\rm s}$	$\rm0.87^{+0.02}_{-0.02}$	$\rm0.63^{+0.01}_{-0.03}$
$\ell_{\rm nth}/\ell_{\rm h}$	$\rm0.11^{+0.02}_{-0.02}$	<0.04
$\tau$	$\rm 8.4^{+1.5}_{-0.7}$	$\rm 8.4^{+0.1}_{-0.2}$
p	$\rm 1.7^{+1.1}_{-0.6}$	[1.7]
$\gamma_{\rm min}$	$\rm 1.15^{+1.54}_{-0.15}$	[1.15]
$\gamma_{\rm max}$	[12]	[12]
F-test	$4 \times 10^{-11}$	0.07
$E_{\rm l}$ (keV)	$\rm 6.7^{+0.1}_{-0.1}$	$\rm 6.7^{+0.1}_{-0.1}$
$\sigma_{\rm l}$ (keV)	$\rm0.2^{+0.1}_{-0.1}$	$\rm0.2^{+0.1}_{-0.1}$
$I_{\rm l}^{b}$	$\rm 4.4^{+1.3}_{-0.8}$	$\rm 4.8^{+2.2}_{-0.8}$
$EW_{\rm l}$ (eV)	$\rm 32^{+9}_{-6}$	$\rm 33^{+15}_{-6}$
$L_{\rm bb}/L_{\rm tot}$	0.11	0.11
$L_{~0.4-30~{\rm ~keV}}^{\rm c}$	1.44	1.46
$L_{~30-200~{\rm ~keV}}^{\rm c}$	0.019	0.006
$\chi ^2$ /d.o.f.	143/142	185/141

$^{\rm a}$ In units of 10²² cm^-2.
$^{\rm b}$ Total photons in the line in units of 10^-3 cm^-2 s^-1.
$^{\rm c}$ Unabsorbed luminosity in units of 10³⁸ erg s^-1.

Source LaTeX | All tables | In the text

	1 Introduction
	2 Observations and data analysis
	3 Results
	4 Discussion
	5 Conclusions
	References